Digit-Span Task#

A classic digit-span task for expyriment.

Configuration#

The experiment can be configured in the config.conf file distributed alongside the task. For the configuration of the [GENERAL] block see Configuration.

Experiment Design#

The experiment design is covered in the [DESIGN] section of the configuration file. The required configuration for experiment design covers the amount of blocks as well as the amount of trials per block. For example:

[DESIGN]
blocks = 1
# * number of trials per block, can vary by block
trials = 10

Optional arguments are described below with their default values:

# * the length of the starting sequence as a whole number
starting_length = 4
# * the type of the sequence to be displayed;
# one of numeric, alphabetic, or ALPHABETIC
sequence_type = numeric
# * whether or not to ask the participant to
# repeat the sequence in reversed order (yes/no)*
reverse = no

# the duration of stimulus display in ms
duration_display = 800
# the break between two stimuli in ms
duration_break = 200

The number of trials, as well as starting length, sequence type, and reversal of sequence (indicated by *) can either be set as one value for the whole experiment, or one value per block. So in case of two blocks, it is possible to have sequence_type = numeric or starting_length = 5, 15; in this case blocks would use numeric stimuli, but they would start with sequences of length 5 and 15 respectively.

Appearance#

The experiment appearance is covered in the [APPEARANCE] section of the configuration file; there are no required arguments. In the following, the default options are listed.

[APPEARANCE]
# offset of the displayed numbers;
# the first value is x offset, the second value y offset
stimulus_offset = (0, 0)
# offset of the input box
input_offset = (0, 0)
# the colour of the stimulus in RGB values
stimulus_colour = (255, 255, 255)
# scale of the stimulus compared to normal text
stimulus_text_size_scale = 6
# scale of the input filed compared to normal text
input_text_size_scale = 3

[ANDROID]
## android specific configuration ##
# offset of the input field (see above) as it might overlap
# with the on-screen keyboard
input_offset = (0, 200)

Logging the Experiment#

What should be logged is described in the [LOG] section of the configuration file. For a general overview on their configuration, see here. The available fields that can be logged are as follows:

• settings, resembling the input to the experiment (may vary per block): reverse, starting_length, trials, sequence_type
• computed data per trial: sequence, sequence_length
• the user response: user_input
• analyses of the user response¹:
  • correct : can be True, False
  • total_match : the amount of matching digits/characters
  • longest_match : the longest continuous match
  • initial_match_answer : the number of correct digits/characters at the beginning of the answer
  • initial_match_sequence : the number of correctly reproduced digits/characters at the beginning of the given sequence
  • similarity : a similarity score calculated as 2 * M / T with M = number of matching digits/characters and T = length of the answer + length of the presented sequence

Example#

A screencast of the first few trials of a Digit Span Task with standard configuration.